A093404 - OEIS

A093404

Primes of the form 70*R_k + 9, where R_k is the repunit (A002275) of length k.

79, 777777777777777777777777777777777777777777777777777777777777777779, 77777777777777777777777777777777777777777777777777777777777777777777777777777777777779, 777777777777777777777777777777777777777777777777777777777777777777777777777777777777777779

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OFFSET

1,1

COMMENTS

Primes of the form (7*10^k + 11)/9. - Vincenzo Librandi, Nov 16 2010

LINKS

Table of n, a(n) for n=1..4.

Makoto Kamada, Prime numbers of the form 77...779.

Index entries for primes involving repunits

MATHEMATICA

Select[Table[FromDigits[PadLeft[{9}, n, 7]], {n, 100}], PrimeQ] (* Harvey P. Dale, May 09 2012 *)

CROSSREFS